168 Mr, De la Beche on the Geology 



schist of the vicinity of Ockham in every thing- but colour. They are here 

 dark-coloured. These rocks traverse the point of land, named at its extremity 

 Hope's Nose; and upon them the limestone of that place appears to rest. 



Small trap veins are observable both in this rock and the red grit of Mead- 

 foot-sands. 



Grauwacke. 



A very small portion of this rock comes within the scope of the present 

 communication. The old red sandstones pass into grauwacke between Ock- 

 ham and Westerland, at which latter place there is a cjuarry of grauwacke 

 rather micaceous. It contains the vertebral columns of encrinites, corals, and 

 bivalve shells. The schist is used to line the interior of the neighbouring- 

 lime-kilns. The dip is E.S.E. about 45°. 



Trap Rocks. 



On the east of Babbacombe, trap rocks advance into the sea and form a 

 small headland. They consist principally of greenstone, varying in grain, and 

 containing abundantly particles of iron pyrites; some of it approaches the cha- 

 racter of a reddish sandstone, and the whole is occasionally traversed by veins 

 of quartz, jasper, and very rich iron ore. Between this headland and the 

 compact, and sometimes semi-crystalline limestone of the main land, argilla- 

 ceous shale is interposed. 



Another small headland, on the west of Babbacombe, is formed of green- 

 stone and greenstone porphyry. Very often the rock assumes a porphyritic 

 and amygdaloidal character at the same time, the amygdaloidal cavities being 

 filled with carbonate of lime. In all cases, iron pyrites, often in cubical cry- 

 stals, is disseminated through the mass : — calcareous and quartz veins traverse 

 the trap, particularly on the Babbacombe side. 



This trap has evidently been protruded into the argillaceous shale from 

 beneath : the strata are cut off and twisted by it ; considerable portions also 

 of the shale are included in the trap. The limestones, forming the upper part 

 of the cliff, rest on the shale, and are also disturbed. 



From hence north-west to Oddicombe-sands, the same kind of trap is ob- 

 served intermixed with the shale at the base of the cliff, and appears to have 

 forced its way high up among it, and, probably, also among the limestones; the 

 cliff is inaccessible, but presents the appearance of different rocks irregularly 

 mixed. The traj) becomes so altered in its character as it ascends, that the 

 highest portions scarcely deserve the name, presenting, when in contact with the 

 limestone, a base that effervesces and contains green specks and crystals of iron 



